Urinary tract infection Flashcards
Is there any indication for culture of urine from bag specimen
No
Options for urine culture in children that can void on request and in younger children, septic
Void on request->MSU Younger->clean catch Septic->SPA, catheter urine
In a sick child, what to do if positive for UTI and why
Need to still consider other diagnosis, 2% of young children with have asymptomatic bacteruria. Positive dipstick does not rule out possibility of more serious illness.
Important history
May have non-specific symptoms: fever, irritability, poor feeding and vomiting Loin/abdominal pain, frequency, dysuria
Examination
Usually normal May have fever Supra-pubic/loin pain
Acute management- indication for admission, IV antibiotics, gent levels
Indications for admission-
gentamicin and benzylpenicillin
May need fluid resuscitation in shocked infant
Gentamicin levels required prior to third dose.
Consider indications for renal USS investigate full septic screen screen.
Treat with IV antibiotics <6 months.
Consider BC/LP if <1 month
Oral antibiotics: type and duration
Infants and Children Trimethoprim 4mg/kg (150mg max) BD (only tablets generally available in community, RCH pharmacy make 10mg/mL suspension for RCH patients) or Trimethoprim and sulphamethoxazole (8mg-40mg per mL) 0.5 ml/kg (20ml max) BD or Cephalexin 15mg/kg (500mg max) TDS –>
10 days total if <2 years, 7 days if >2 years
When to consider a renal USS to exclude
Atypical
Not responding after 48 hours
Boys < 3months
>6 months if atypical, >48 hours
Required during admission for UTI
Renal USS indicated within 6 weeks and in older children
- For recurrent
Underlying causes of UTI (6)
Obstructed urinary system Vesicoureteric reflux Idiopathic Poor hygeine->kept in wet nappy, wiping back to front in girls Constipation->poor bladder emptying Neurppathic->abnormal spinal function
Causes of obstructed urinary system (5)
Pelviureteric obstruction Renal stones Posterior urethral valve Duplex kidney with obstructed poles Horseshoe kidney
What xsome abnormality associated with horseshoe kidney
Turner
Important history in UTI
Antenatal USS Fever, vomiting, irritability, septic shock, poor feeding, FTT, jaundice, bedwetting, offensive urine, hematuria Poor stream->posterior urethral valves in boys Constipation, deH, spinal disorders FHx renal disease, VU reflux
Examination
Fever, perfusion, HR, jaundice Abdominal pain, palpable kidneys Growth BP Spinal abnormalities Genitalia
Management of pyelonephritis
Admission 2-4 days IV Oral antibiotics for 10 days following
General advice to parents for longer term prevention
Good hygiene Hydration Prompt toileting Avoiding constipation
Renal USS- purpose
Anatomical hydronephrosis VUR Renal cortical damage
DMSA isotope scan
Inject radioisotope- taken up by renal tubule, quantify differential function between two kidneys and show scarring
DTPA renogram
Inject radioisotope, filtered through kidney, shows functional clearance. Cam identify stasis in renal pelvis due to obstruction
Micturating urogram
Catheter passed into bladder and contrast injected to detect reflux up into ureters with antibiotic cover
Consequences of posterior urethral valves
Bladder hypertrophy bilateral hydronephrosis renal impairment
Value of SPA
- Do not delay antibiotics for sick child
- Too young for MSU, high probable of UTI, unwell needing more invasive
- Always send for culture
- Any growth usually indicates infection
Value of catheter specimen
- Failed SPA
- SPA still preferred
- Always send for sulture
- Any growth >10 ^3 usually indicates infection
Value of clean catch
- Unable to void on request
- Not too unwell
- Parents to catch or dish used
Value of MSU
- Can void on request
- Wash genitalie with water and dry
- Do not collect first few mls
- Pure growth >10 ^8 indication of infection
Value of full ward test
- Screening only
- If UTI suspected need NCS
Important points when testing urine
- Blood and protein are unreliable markers of UTI
- Not all organisms produce nitrites and nitrites take time to develop in urine and so have poor sensitivity.
- Not all patients with UTI have pyuria, especially the very young & neutropenic patients. Leucocyte esterase can only be detected with relatively high WBC counts in urine. So the test has low sensitivity.
- Leucocytes from local sources (vagina, foreskin) may contaminate urine. Leucocytes appear in the urine in many other febrile illnesses eg URTI, pneumonia, meningitis etc. So the specificity is low.
